This invention relates generally to electrical connector components and, more particularly, to jacks for modular plug connectors which terminate multi-conductor cordage. More specifically, this invention relates to such jacks which serve to conduct to ground interference-causing electromagnetic and radio frequency signals carried in a conductive shield surrounding the conductors of a cord and, if desired, for providing shielding to control any leakage of such radiation from within the jack as well as suitably attenuating externally generated high frequency signals passing into the jack.
It has been recognized that digital-based electronic equipment is a major source of electromagnetic (EMI) and radio frequency (RFI) interference. Such interference has become a problem due at least in part to the movement away from metal and towards plastic as the material from which connector housings are formed. Plastics generally lack the shielding effectiveness inherent in metal housings.
In order to prevent or at least substantially control the emission of interference-causing electromagnetic and radio frequency radiation from multi-conductor cordage used in digital-based electronic equipment and to provide at least some protection from interference-causing signals radiated from external equipment, such cordage has conventionally been provided with "shielding" in the form of a continuous sheath of conductive material between the outer insulation jacket of the cord and the insulated conductors, the shield surrounding and enclosing the conductors along their length. The shield can be formed of any suitable conductive material such, for example, as thin Mylar having a surface coated with aluminum foil, braided metallic material, and the like. The shield acts to suppress or contain the interference-causing electromagnetic and radio frequency signals radiating outwardly from the cordage conductors and, conversely, to prevent such high frequency signals generated by external equipment from causing interference in the conductors.
So-called modular plug connectors are finding increased use in terminating multi-conductor cordage, shielded in the manner described above, through which digital information is transmitted. For example, modular plug connectors are finding increased use in terminating multi-conductor cordage used in home and office computers for connecting the computers with peripheral components, in data communication applications generally, in electronic games, in telephone communication networks and in similar digital applications.
Various configurations of such modular plug connectors are disclosed in patents assigned to Western Electric Company, Inc., such for example as U.S. Pat. Nos. 3,699,498; 3,761,869; 3,860,316; and 3,954,320. Another advantageous configuration of a modular plug connector is disclosed in U.S. Pat. No. 4,211,462 assigned to Stewart Stamping Corporation, assignee of the instant application. The disclosures of the above-mentioned patents are incorporated by reference herein.
Jacks for modular plug connectors are also known. For example, reference is made to the following patents assigned to Bell Telephone Laboratories, Incorporated: U.S. Pat. Nos. 3,990,764; 3,850,497; and 4,224,485.
It has been conventional to ground the conductive EMI/RFI shield of a multi-conductor cord terminated by a modular plug connector by means of a so-called "drain wire" which extends through the cord in electrical engagement with the conductive shield. The drain wire is grounded by passing its end out of the connector and connecting it to a grounded terminal to thereby "drain" the radio frequency and electromagnetic radiation signals conducted through the shield and at the same time ground any electrostatic charge that the shield may have acquired.
However, this technique has not satisfactorily eliminated the problem of interference caused by such radiation. Specifically, it has been found that there is still a tendency for EMI and RFI to result from the leakage of electromagnetic and radio frequency radiation signals from the cordage in the region at which the modular plug connector is inserted into the jack socket. Moreover, it is not uncommon for high frequency signals radiated from nearby equipment to pass through the jack and cause interference in the cord conductors.
For this reason, it has been proposed to modify the modular plug connector by incorporating a shield terminating contact pin as part of the connector itself. Thus, it has been proposed in application Ser. No. 512,375 filed July 11, 1983 and an application entitled Improved Modular Connector For Terminating EMI/RFI Shielded Cordage And Cord Terminated Thereby filed simultaneously herewith, both applications assigned to the assignee of the instant application, to provide a pin-shaped contact formed of electrically conductive material through a passage formed in a side wall of the modular plug connector so that one end of the contact is exposed externally at the side of the connector while a portion of the length of the contact electrically engages a region of the foil shield surrounding the conductors of the cord whose end is terminated by the connector. It is further proposed in said applications that a conventional jack be provided with a grounded contact which engages the exposed end of the pin contact of the modular plug connector upon its insertion into the jack receptacle to ground any electrostatic charge in the shield and conduct the electromagnetic and radio frequency signals carried in the shield to ground thereby preventing leakage of radiation from the connector. The particular construction of the modular plug connector forms no part of the present invention.
It will be understood that it is desirable to provide a jack for a modular plug connector of the type described above, namely, wherein a shield terminating contact pin is incorporated as a part of the modular plug connector itself, which will reliably conduct interference-causing electromagnetic and radio frequency signals from the shield terminating contact pin of the connector to ground and which at the same time will additionally provide an effective EMI/RFI shield for the connector itself to suitably attenuate any radiation which may either leak from the region of the connector or be generated by external equipment.